Draft trap



Patented Dec. 26, 1950 UNITEDy STATES Vernxl|-:1\rl OFFICE 1 This invention relates to means" for blocking vertical shaftsor passageways of buildings, such as elevator shafts, dumbwaiters, laundry shafts, hatchways, Ventilatingv shafts, and the like', through which hot air orsmoke or other products of combustion have a tendency to ilow'upwardly in case of a building or large shipca'tching fire and thus cause the fire to quickly spread through# out the building or other structure, it being one object of the invention to provide blocking means for the shaft or passage consisting of doors or barrier plates which are normally in a raised position close to sides of the shaft land so mounted that when released they may jmove downwardly to a closed position across the shaft where they will serve very effectively to shutoff draftthrough the shaft and confine the fire to thel area below the closed doors.

vAnother object of the invention is to provide a barrier consisting of doors or closure plates which are releasably held ina raisedv position against side walls of the shaft by latches, that while the doors .may be automatically f released when the latches are subjected to excessive heat, the latches may be manually moved to a releasing position by aperson who notices the name or excessive heatfcoming upwardly through a shaft and thereby permit the doors to be closed sooner than would be the case if automatic releasing of the doors was the solemeans depended upon for effecting closing ofthe doors.l l

Another object of the invention isto provide closures or barriers for a shaft o'r passage which are ypivotally mounted close to opposite side walls of a shaft for movementfrom a raised position to a lowered or closed positionacross the shaft, means being providedmfor checking downward swinging movement of thedoors or closure plates and thus prevent danger of the doors being brof ken loose at their hinged sides byviolently striking .each other as they move to the closed position.

Another object of the invention is to provide closures for a shaft or passage which is of simple construction and very eiicient in operation.

With the foregoing and other objects in view, the invention consists of a specialv construction and arrangement of parts illustrated in the accompanying drawing wherein:

Figure 1 is a view showing a shaft in cross section and looking down upon `the improved closures for the shaft, the closures being shown in the normally opened position by full lines andl indicated in a closed position by dotted lines.

Figure 2 is a view taken along the line 2--2 l. 2 of Figure 1 and showing the shaft in vertical section and the closures in side elevation.

IFigure 3 is a sectional view upon an enlarged scale taken along the line 3-3 of Figure 1. y VFigure 4 is an enlarged view of a latch for holding a door in its raised or opened position.

Figure 5 is a sectional view taken vertically through the latch along the line 5-5 of Figure 4. The shaft or passage indicated by the numeral I' maybe an elevator shaft or similar shaft or vertically extending passage in a building, ship or the like` When a rhre starts in the basement orene yof the lower floors of a building ame, smoke and other hot products of combustion are carried upwardly through an lelevator shaft, or like passage, and this causes the lire to quickly spread throughoutthe building, whereas if the shaft or passage is blocked to prevent an updraft lthrough it, the re lcould be confined t0 the basement o-r lower floor where it started.-

In orderto permit the shaft or passage to be blocked, I have provided doors or barrier plates `2 which are of such dimensions that when they are in a llowered or horizontally extending closed position they extend across each other from opyertically in close parallel relation'to the walls Where they will be out of the way and not prevent an elevator from freely moving vertically in the shaft.` When the doors are released, their weight will cause them to move away from the shaft walls and downwardly to a horizontal position with their free end edges in such close proximity to each other that the two doors constitute a barrier which blocks the shaft and prevent an updraft through the shaft. The two doors are releasably held in a normally raised or open position by latches 4 which are formed of metal and each of which has a wide and flat shank 5 formed of hard metal and at the lower end of its shank a bill 6 which is formed of soft fusible metal which is strong enough to hold a door in its raised position by overlapping engagement with the upper free end of the door but capable of being melted by flame or hotI products of combustion moving upwardly through the shaft. When the bill is melted to such an extent that it can no longer hold the door in the raised position, the weight of the door will cause it to swing downwardly to a closed position, and since the two doors will simultaneously be released and move to the closed position, they will block the shaft and prevent further updraft through the shaft.

The latches or keepers have their Shanks secured against mounting plates 'I by screws 8 which pass through vertically extending slots 9 formed in the shanks of the latches and have threaded engagement with the mounting plates, the screws also passing through plates I which are provided so that the latches will be spaced from the plates 'I and thus caused to slide easily in a vertical direction. Eyes II are mounted at upper ends of the latches and through these eyes are secured lower ends of cables or wires I2 which extend upwardly in the shaft I and are in such positions that they may be grasped and upward pull exerted to manually move the latches to a releasing -position in case some one should discover a nre and wish to release the doors for closing movement before the doors are automaticallyi released by melting of the billsv of the latches. It will thus be seen that the doors may befautomatically released or manually released and move into position to block the shaft.

If the doors were allowed to have uncontrolled downward swinging movement to a closed positionA and suddenly brought to a stop by engagement with each other or by their hinged ends contacting the walls of the shaft, the hinges might be broken and the doors drop vdownwardly .through the-shaft or move toA such a position .that-the shaft would not be-.properly blocked. In order to prevent this, each door has attached to its free end a cable I3 which is attached at its upper or outer end to a screw eye I4 carried by the door. The cables extend through openings-t5 formed through upper ends of the mounting plates and are trained about pulleys I6 carried by brackets II fixed to the inner faces of the mountingplates. From the pulleys the cables I3 extend downwardly through openings in the brackets, and at their lower ends carry blocks I8 which to some extent counter balance the weight Aof the doors but allow them to swing quickly to a closed position.

. The blocks. or counterweights move vertically in pockets I9 formedy vertically in the side walls of the shaft and closed by the mounting plates l", andr when the doors swing downwardlyl to.- wards' a .closed position and the cables I3 are drawn. upwardly and outwardly, the blocks will be drawn v,upwardly until they make contact with helical. springs 2li mounted under the brackets ,and through which the cables pass. Engagement ofthe blocks with the lower ends of the springs will compress the springs and check upward movement of' the blocks, and downward movement of the door will be slowed suiiiciently to -prevent the doors from being broken by crashing'v movement to a closed position. After a re 4 has been extinguished, the doors will be returned to a raised or open position and new latches applied to hold the doors open or the latches pulled upwardly out of the way until the doors are opened and then allowed to return to a securing position if movement of the latches to a releasing position was manually effected and their bills not melted off during the re.

It will be seen from the foregoing description that I have provided a comparatively simple, inexpensive and eflicient means for carrying out the various objects of the invention, and while I have described the elements best adapted to perform the functions set forth, it is apparent that various changes in form, proportion and in the minor details of construction may be resorted to,

v without departing Vfrom the spirit or sacrificing any of the principles of the invention.

Having thus described the invention, what is claimed is:

In combination. with a vertical shaft having opposed-side walls formed with vertically extending pockets, plates mounted against said side walls and covering said pockets, doors hinged to saidwalls for vertical movement from .a raised position. close tothe walls to a closed position in which they extend' towards each other in closing,r relation to the shaft with their free ends meeting midway the Width of the shaft, latches carried. by said plates and movable into and out of position to engage said doors and releasably hold the doors in the raised position, brackets extending from said plates into said pockets, pulleys car'- ried by said brackets and disposed over the brackets opposite openingsin the plates, helical springs STERLING E. NORCROSS,

REFERENCES CITED Thel following references are ci record in the r'ileof this patent:

UNITED STATES PATENTS Number Name Date 466.819 Banks Jan. 121892 516,937.. .Wernple .Mar-.5.318951 596,946 Rowntree danni, 1893 1,085,705 Schnuck Feb. 3, 1914 1,579,677 Tomkinson Apr. 5, 1926 Flohberger June 30, 1942 

